1. Field of the Invention
The invention generally relates to a fin-type field effect transistor (FinFET), and more particularly, to a double-gated FinFET structure having electrically isolated gates and a method for manufacturing the double-gated FinFET structure.
2. Description of the Related Art
As transistor design is improved and evolves, the number of different types of transistors continues to increase. A fin-type field effect transistor (FinFET) is a type of transistor that has a fin, containing a channel region and source and drain regions. A double-gated FinFET is a FinFET with first and second gate conductors on either sidewall of the fin. The gate conductors cover the channel region of the fin, whereas the source and drain regions of the fin extend beyond the coverage of the gate conductors. FinFETs are discussed at length in U.S. Pat. No. 6,413,802 to Hu et al. (hereinafter “Hu”), which is incorporated herein by reference. Certain circuit applications, including equivalent well-bias control, multiple threshold Complimentary Metal Oxide Semiconductor (CMOS) structures and analog circuits, can benefit from having independently controlled gates on the same FinFET. Additionally, using one gate to adjust threshold voltage will allow device designers to avoid the dopant fluctuation scaling limit. In order to independently control the first and second gates of a doubled-gated FinFET, the gates must be isolated. Isolating the first and second gates can be difficult.